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My a/c works fine when the car is moving, but not when I stop at a stop sign, red light, etc. The fan runs okay, but the compressor won't remain engaged unless I'm moving. The compressor will kick in (I can feel the load on the engine), and the compressor remains engaged for maybe 5-10 seconds, and then it kicks out. I have a temperature gauge in the dash vent, and the temp runs about 40F when the car is moving, but if I'm sitting still, it may be 70-80-90F, depending on how long I sit there? Help?
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
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Joined: Jan 2003
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Hard-core CEG\'er
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I searched my manual and came up with this.
A/C Clutch Control Relay
The manual A/C-heater electrical system uses a number of relays and pressure sensitive switches to control system functions. These components are:
A/C clutch control relay
A/C wide open throttle (WOT) relay
A/C pressure cut-off switch (19D594)
A/C cycling switch (19E561)
A/C-heater blower relay
The A/C WOT relay controls A/C clutch operation through the A/C clutch control relay based on information received from the A/C cycling switch, the A/C pressure cut-off switch and the powertrain control module (PCM) (12A650).
The A/C WOT relay deenergizes the A/C clutch control relay and de activates the A/C clutch (2884) when signalled by the powertrain control module. The A/C clutch could be deactivated in this manner under the following conditions:
engine start-up
wide open throttle (WOT)
during low engine idle conditions
excessively high engine temperature
Not sure if this might be your problem.
Maybe someone else has more insight.
1996 2.5LT V6 Contour ATX My Tour+help/info pics
E0 rims, Gutted Pre-Cats,CTA Custom Exhaust & Intake, Diablo Chip.
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Joined: Mar 2002
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A quick guess is that you have low system pressure. You need a minimum pressure while the compressor is running, or else the compressor just keep cycling on and off. I could see that maybe with marginal low pressure you could run it with higher enigne rpm, but at lower rpms maybe you aren't getting enough pressure to keep it activated? Buy the 12 dollar recharge kit with the gage on it - just remember the compressor MUST be running to get a real pressure reading and recharge the system - so if it is cycling on and off you will need to jumper the pressure switch to keep the compressor going. I learned this with my wifes leaky AC system on our old Neon that we knew we were getting rid of soon. I let it sit all winter and just recharged it for the summer months - buyer beware of high mileage trade ins 
97 Contour SE MTX
K&N 3530, UR UDP, 19# Injectors, mystery mod, FMS wires, Fordchip.com chip, SVT: TB, Flywheel, clutch, exhaust
04 Grand Caravan SXT
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I don't think it's the pressure. At least, it doesn't seem to be low. I've checked it with one of the interdynamics gauges, and it seems okay. Also, revving the engine doesn't help. When I'm stopped with the engine running, I can rev the engine to any rpm, and the ac still won't work.
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
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Joined: May 2004
Posts: 1,262
Zippy Zetec on his last legs.
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Zippy Zetec on his last legs.
Joined: May 2004
Posts: 1,262 |
does it make any ticking or clacking noises??? a/c clutch if so...
Regards, Cole.
Relegating to troll status sometime this week.
New Whip: 1990 Lexus ES250.
Old Hotness: 1995 GL MTX Zetec *IN TRIAGE*
"I had a little friend once, but it dont move no more...  "
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This is an interesting one...
Think about what does work:
Compressor
Clutch
System charge is just fine, otherwise 40F vent temperature would never be attained at any road speed.
Think about what can make it not work as given by the service CD quote above:
Engine running too hot (or the computer thinks it is too hot)
Engine idling too low (is it?)
Cooling fan not operational while the car is stopped (is it? - if not, the high pressure cutout swiitch will quickly activate as high side pressures quickly climb when not moving)
Computer thinks the engine is at WOT when it is not
Computer is correctly attempting to control the A/C relays, but a fault in the relays is preventing proper operation Iless likely).
Will the A/C work immediately when the car is cold started before it moves?
A couple of questions that wil help pin down the likely culprit....
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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Originally posted by projectSHO89:
(1) Engine running too hot (or the computer thinks it is too hot)
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I do have cooling problems, but I dont' think that's the issue here. The AC doesn't work properly at idle, even when the temperature gauge indicates N-O-R-M)
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(2) Engine idling too low (is it?)
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No, the idle is okay. It may dip to 500 for a second when the ac clutch kicks in, but it will go back to 900-1000 in a second or two. I've also held my foot on the accelerator, and kept the rpm's at 2-3K for a few minutes, and the ac still didn't work
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(3) Cooling fan not operational while the car is stopped (is it? - if not, the high pressure cutout swiitch will quickly activate as high side pressures quickly climb when not moving)
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You may be on to something here. I suspect that this is part of the problem. No, the cooling fans aren't doing what they are supposed to do. AT least, I don' think they are. The cooling fans are intermittent, and turn on and off, even when the ac is turned on. The fans run for a few seconds, and then turn off for maybe a minute or two. The do not run continuously, even when the ac is on.
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(4)computer is correctly attempting to control the A/C relays, but a fault in the relays is preventing proper operation Iless likely).
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also a possibility.......I've suspected the relays may be fouled up. My cooling fans don't work properly, and the relay could be the problem.
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(5)Will the A/C work immediately when the car is cold started before it moves?
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When I first start the car, the ac will work for a brief period of time, maybe a minute or so
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Yesterday, after driving for 10 miles or so, I left the engine running and I hooked up a gauge to the low pressure side of the ac lines. The gauge would read around 100 or above when the ac was not turned on. When I turned the ac on, the gauge would drop to around 40, stay there a few seconds, and then the compressor would kick off, and the gauge would climb to around 70 or so before the compressor kicked back in again. It would cycle on and off, and I could feel the "cold" in the low pressure lines. It appears that the problem is that the unit turns off too quickly. While the ac was cycling on and off, the air coming out of the vents was around 70 or so, rather than 40.
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
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